JP4013274B2 - Valve timing control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a valve timing control device for an internal combustion engine in which the opening / closing timing of at least one of an intake valve and an exhaust valve of the internal combustion engine can be changed according to an operating state.
[0002]
[Prior art]
Conventionally, as a prior art document related to a valve timing control device for an internal combustion engine, one disclosed in Japanese Patent Laid-Open No. 7-11980 has been known.
[0003]
In this system, in the feedback control of the valve timing adjustment using the valve timing control mechanism driven by oil pressure using the lubricating oil of the internal combustion engine, the learning value is reflected on the advance side and the duty value is set on the retard side. The adoption of this technique shows that the learning time is shortened and at the same time, accurate valve timing adjustment is performed without being affected by manufacturing variations.
[0004]
[Problems to be solved by the invention]
By the way, in a valve timing control mechanism that is driven hydraulically by using lubricating oil of an internal combustion engine, at the start of driving from a predetermined control rotation angle to an advance side or a retard side, or from an advance side direction to a retard side direction When the valve timing is changed from the retard side direction to the advance side direction, a hysteresis phenomenon occurs due to the effect of static friction, etc., so that even if an attempt is made to perform accurate valve timing adjustment, the desired control rotation angle is not reached. There was a bug.
[0005]
Therefore, the present invention has been made to solve such a problem, and an object thereof is to provide a valve timing control device for an internal combustion engine that can perform accurate valve timing adjustment without being affected by static friction or the like.
[0006]
[Means for Solving the Problems]
According to the valve timing control apparatus for an internal combustion engine according to claim 1, the corrected rotation angle portion that gives a minute amplitude fluctuation at a predetermined frequency by the control rotation angle correction means with respect to the control rotation angle calculated by the relative rotation angle control means. Superimposed. Then, by using the control rotation angle on which the correction rotation angle is superimposed, the control duty ratio for the actuator is always slightly changed, and a forced minute vibration is given to the valve timing control mechanism. Specifically, with respect to a control rotation angle that is a deviation between a relative rotation angle that is a phase difference between a drive shaft and a driven shaft of a spool valve that adjusts the hydraulic pressure supplied to the valve timing control mechanism, and a target relative rotation angle. A basic control current to be supplied to the linear solenoid is set, and a dither signal for a correction rotation angle that gives a minute amplitude fluctuation at the predetermined frequency is superimposed on the basic control current for correction. Then, in the valve timing control mechanism, the valve timing is started from the predetermined control rotation angle to the advance side or the retard side, or from the advance side to the retard side, or from the retard side to the advance side. When the angle is changed, it is possible to eliminate a control rotation angle error due to a hysteresis phenomenon caused by frictional fluctuation or the like. For this reason, the effect that the advance amount or the retard amount when the valve timing is changed by the valve timing control mechanism corresponding to the change of the control duty ratio can be controlled extremely accurately is obtained.
[0007]
In the valve timing control device for an internal combustion engine according to claim 2, the magnitude of the amplitude fluctuation in the correction rotation angle superimposed on the control rotation angle with respect to the valve timing control mechanism is based on the operating state of the internal combustion engine, the relative rotation angle, and the control rotation angle. Is set. That is, the control rotation angle error at the time of changing the valve timing can be appropriately eliminated by superimposing the correction rotation angle corresponding to the change of various control conditions on the control rotation angle. As a result, there is an effect that the advance amount or the retard amount when the valve timing of the VVT 50 corresponding to the change of the control duty ratio can be controlled extremely accurately.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples.
[0009]
FIG. 1 is a schematic configuration diagram showing a double overhead cam type internal combustion engine to which a valve timing control device for an internal combustion engine according to an embodiment of the present invention is applied and its peripheral devices.
[0010]
In FIG. 1, reference numeral 10 denotes an internal combustion engine, and a driving force is transmitted from a crankshaft 11 as a drive shaft of the internal combustion engine 10 to a pair of chain sprockets 13 and 14 via a chain 12. The pair of chain sprockets 13 and 14 rotated in synchronization with the crankshaft 11 are provided with a pair of camshafts 15 and 16 as driven shafts. The valve is driven to open and close.
[0011]
A crank position sensor 21 is disposed on the crankshaft 11, and a cam position sensor 22 is disposed on the camshaft 15. The pulse signal θ1 output from the crank position sensor 21 and the pulse signal θ2 output from the cam position sensor 22 are input to an ECU (Electronic Control Unit) 30.
[0012]
The ECU 30 is configured as a logical operation circuit including a CPU as a known central processing unit, a ROM storing a control program, a RAM storing various data, an input / output circuit, a bus line connecting them, and the like.
[0013]
In addition to these signals, the ECU 30 receives an intake air amount (intake air amount) GN per unit engine speed from an air flow meter (not shown) corresponding to the operating state of the internal combustion engine 10, and a water temperature sensor (not shown). Various sensor signals such as the coolant temperature THW are input, and a relative rotation angle VT and a target relative rotation angle VTT of the camshaft 15 with respect to a crankshaft 11 described later are calculated. The linear solenoid 41 of the spool valve 40 is duty controlled by a drive signal from the ECU 30, and the oil in the oil tank 45 is provided to one camshaft 15 through the supply oil passage 47 by the pump 46. The valve timing control mechanism (Variable Valve Timming Control Mechanism: hereinafter simply referred to as “VVT”; hatched portion in FIG. 1) 50 is pressure-fed. By adjusting the amount of oil supplied to the VVT 50, the camshaft 15 is rotatable with a predetermined phase difference with respect to the chain sprocket 13, that is, the crankshaft 11, and the camshaft 15 is the target. The relative rotation angle VTT can be set. Note that the oil from the VVT 50 is returned to the oil tank 45 through the discharge oil passage 48.
[0014]
Here, when the crankshaft 11 rotates once and N pulses are generated from the crank position sensor 21, N pulses are generated from the cam position sensor 22 by one rotation of the camshaft 15. When the maximum timing conversion angle value of the camshaft 15 is θmax ° CA (crank angle), the number of pulses N is set so that N <(360 / θmax). Thus, when calculating the relative rotation angle VT, the pulse signal θ1 of the crank position sensor 21 and the pulse signal θ2 of the cam position sensor 22 generated following the pulse signal θ1 can be used.
[0015]
Next, based on the flowchart of FIG. 2 showing the processing procedure of the ECU 30 used in the valve timing control apparatus for an internal combustion engine according to an example of the embodiment of the present invention, refer to the maps of FIG. 3 and FIG. I will explain. Here, FIG. 3 is a map for calculating the target relative rotation angle VTT from the engine speed Ne and the intake air amount GN, and FIG. 4 is a map for calculating the basic control current IBC with respect to the relative rotation angle deviation. This routine is repeatedly executed by the ECU 30 every predetermined time.
[0016]
In FIG. 2, first, in step S101, it is determined whether an execution condition for the VVT 50 is satisfied. Here, the execution condition for the VVT 50 is not satisfied when the engine speed Ne after starting the internal combustion engine 10 is a predetermined engine speed, for example, less than 500 rpm, and the coolant temperature THW is a predetermined temperature, for example, less than 0 ° C. . That is, when the engine speed Ne is less than 500 rpm, the internal combustion engine 10 is not yet in a stable idle operation state with little elapsed time after starting, and when the cooling water temperature THW is less than 0 ° C., the oil temperature for driving the VVT 50 can be similarly estimated to be low. This is because the viscosity seems to be too high.
[0017]
When the determination condition in step S101 is satisfied, the process proceeds to step S102, where the output signal θ1 of the crank position sensor 21 and the output signal θ2 of the cam position sensor 22 are used as various sensor signals, and further, the parameters represent the operating state of the internal combustion engine 10. The engine speed Ne and the intake air amount GN are read. Next, the process proceeds to step S103, where the relative rotation angle, which is the current phase difference of the camshaft 15 with respect to the crankshaft 11, from the output signal θ1 of the crank position sensor 21 and the output signal θ2 of the cam position sensor 22 read in step S102. VT (= θ1−θ2) is calculated.
[0018]
Next, the process proceeds to step S104, and the target relative rotation angle VTT that is the current target phase difference is calculated from the map shown in FIG. 3 based on the engine speed Ne and the intake air amount GN read in step S102. Next, the process proceeds to step S105, and the map shown in FIG. 4 is based on the relative rotation angle deviation (VTT−VT) between the relative rotation angle VT calculated in step S103 and the target relative rotation angle VTT calculated in step S104. The basic control current IBC supplied to the linear solenoid 41 of the spool valve 40 as an OCV (Oil-flow Control Valve) is calculated.
[0019]
In step S106, a dither signal as described later is set. Next, the process proceeds to step S107, where the dither signal set in step S106 is superimposed on the basic control current IBC calculated in step S105, and finally the control current Ic for controlling the VVT 50 is calculated. Exit. On the other hand, when the determination condition of step S101 is not satisfied, the routine proceeds to step S108, where the control current Ic for the VVT 50 is turned off, and this routine is terminated while the VVT 50 is held at the most retarded side.
[0020]
FIG. 5 is an explanatory diagram showing the dither signal set in step S106 of the routine described above.
[0021]
The dither signal is a signal having a relatively high frequency (several tens to several hundreds of Hz) as shown in FIG. 5 as the amount of fluctuation as the + (plus: addition) side set value and the-(minus: subtraction) side set value. (Indicated by a solid line in FIG. 5), and superimposing on the basic control current IBC (indicated by a broken line in FIG. 5) causes minute vibrations to the original current value. Thus, according to the control current Ic in which the dither signal is superimposed on the basic control current IBC in step S107 of the above-described routine, the control duty ratio with respect to the linear solenoid 41 is always slightly fluctuated. On the other hand, a forced minute vibration is given. Then, in the VVT 50, the valve timing is changed at the start of driving from the predetermined control rotation angle to the advance side or retard side, from the advance side to the retard side, or from the retard side to the advance side. The control rotation angle error due to the hysteresis phenomenon caused by friction fluctuations can be eliminated. As a result, it is possible to control the amount of advance or retard when the valve timing of the VVT 50 corresponding to the change of the control duty ratio is very accurately controlled.
[0022]
Next, the setting of the dither signal will be specifically described.
[0023]
First, the case where a dither signal is set according to the current operating state will be described using the map of FIG. A basic dither signal DB1 for the engine speed Ne [rpm] is calculated from the map of FIG. As shown in the map of FIG. 6 (a), when the engine rotational speed Ne as the operating state is lower than the predetermined rotational speed, the hydraulic pressure generated is also low, so the basic dither signal DB1 is lower than the engine rotational speed Ne. As the value becomes, the positive side set value and negative side set value with respect to the median value are gradually increased to overcome the static friction. Further, a correction coefficient K1 for the cooling water temperature THW [° C.] is calculated from the map of FIG. As shown in the map of FIG. 6 (b), the lower the coolant temperature THW as the operating state, the lower the oil temperature, the higher the viscosity, and the greater the resistance. Therefore, the correction coefficient K1 for the basic dither signal DB1 is lower. As it goes, it is gradually increased from 1.0. Then, by multiplying the basic dither signal DB1 by the correction coefficient K1, a dither signal corresponding to the current operating state is set, and the required control time is shortened and the positioning accuracy with respect to the control rotation angle is improved.
[0024]
Next, a case where the dither signal is set according to the current relative rotation angle VT will be described using the map of FIG. The basic dither signal DB2 with respect to the relative rotation angle VT is calculated from the map of FIG. As shown in the map of FIG. 7 (a), when the relative rotation angle VT is smaller than the predetermined rotation angle, it is gradually increased toward the retard side, and conversely when it is larger than the predetermined rotation angle, it is gradually increased toward the advance angle side. To be overcome. Further, as a correction coefficient for the basic dither signal DB2, a correction coefficient K1 for the coolant temperature THW [° C.] is calculated from the map of FIG. 7B, similar to FIG. 6B, and the map of FIG. Thus, the correction coefficient K2 for the engine speed Ne [rpm] is calculated. As shown in the map of FIG. 7 (c), the correction coefficient K2 for the engine speed Ne is gradually increased from 1.0 as the engine speed Ne becomes lower than the predetermined speed, and conversely as it becomes higher than the predetermined speed. It is made smaller than 1.0 and the hydraulic pressure is corrected. Then, by multiplying the basic dither signal DB2 by the correction coefficient K1 and the correction coefficient K2, a dither signal corresponding to the current relative rotation angle VT is set, and the required control time is shortened and the positioning accuracy with respect to the control rotation angle is improved. Is done.
[0025]
A case where the dither signal is set according to the current basic control current IBC will be described using the map of FIG. The basic dither signal DB3 for the basic control current IBC is calculated from the map of FIG. As shown in the map of FIG. 8A, when the basic control current IBC is in a predetermined current value range, the advance side and the retard side are increased, so that the static friction is overcome. Further, as a correction coefficient for the basic dither signal DB3, a correction coefficient K1 for the cooling water temperature THW [° C.] is calculated from the map of FIG. 8B, similar to FIG. 6B, and the same as in FIG. 7C. The correction coefficient K2 for the engine speed Ne [rpm] is calculated from the map shown in FIG. By multiplying the basic dither signal DB3 by the correction coefficient K1 and the correction coefficient K2, a dither signal corresponding to the current basic control current IBC is set, and the required control time is shortened and the positioning accuracy with respect to the control rotation angle is improved. Is done.
[0026]
As described above, the valve timing control device for an internal combustion engine according to the present embodiment includes a chain 12 that transmits a driving force from a crankshaft 11 as a driving shaft of the internal combustion engine 10 to a camshaft 15 as a driven shaft that opens and closes an intake valve. A VVT 50 which is provided in a driving force transmission system comprising the camshaft 15 and is relatively rotatable within a predetermined angle range; a crank position sensor 21 as a drive shaft rotation angle detection means for detecting the rotation angle θ1 of the crankshaft 11; A cam position sensor 22 as a driven shaft rotation angle detecting means for detecting a rotation angle θ 2 of the cam shaft 15, a rotation angle θ 1 of the crank shaft 11 detected by the crank position sensor 21, and a cam shaft detected by the cam position sensor 22 ECU 30 that calculates a relative rotation angle VT that is a phase difference with respect to 15 rotation angles θ 2. And the target of the rotation angle of the crankshaft 11 and the rotation angle θ2 of the θ1 camshaft 15 in accordance with the engine speed Ne and the intake air amount GN representing the operating state of the internal combustion engine 10. A target relative rotation angle calculation means that is achieved by the ECU 30 that calculates a target relative rotation angle VTT that is a phase difference between the relative rotation angle VT calculated by the relative rotation angle calculation means and the target relative rotation angle calculation means. A basic control current IBC corresponding to a control rotation angle that is feedback-corrected according to a deviation from the calculated target relative rotation angle VTT is calculated, and a relative rotation angle that is achieved by the ECU 30 that relatively rotates the camshaft 15 by the VVT 50. A correction circuit that applies a minute amplitude fluctuation at a predetermined frequency to the control means and the basic control current IBC corresponding to the control rotation angle calculated by the relative rotation angle control means. Set the dither signal corresponding to the angular amount, in which and a control rotational angle correcting device achieved by ECU30 that superimposed on the basic control current IBC correction.
[0027]
Therefore, with respect to the basic control current IBC corresponding to the control rotation angle calculated by the ECU 30 that achieves the relative rotation angle control means, the correction rotation angle that gives the minute amplitude fluctuation at a predetermined frequency by the ECU 30 that achieves the control rotation angle correction means. A dither signal set corresponding to the minute is superimposed. Then, by using the control current Ic in which the dither signal is superimposed on the basic control current IBC, the control duty ratio for the linear solenoid 41 is always slightly changed, and a forced minute vibration is given to the VVT 50. Then, in the VVT 50, the valve timing is changed at the start of driving from the predetermined control rotation angle to the advance side or retard side, from the advance side to the retard side, or from the retard side to the advance side. The control rotation angle error due to the hysteresis phenomenon caused by friction fluctuations can be eliminated. For this reason, it is possible to control the amount of advance or retard when the valve timing of the VVT 50 corresponding to the change of the control duty ratio is very accurately controlled.
[0028]
Further, the valve timing control device for an internal combustion engine of the present embodiment includes at least the engine speed Ne and the coolant temperature THW representing the operating state of the internal combustion engine 10, the relative rotation angle VT, and the basic control current IBC corresponding to the control rotation angle. Based on one, the magnitude of the amplitude fluctuation in the dither signal corresponding to the correction rotation angle is set. That is, the magnitude of the amplitude variation of the dither signal as the correction rotation angle is set based on the parameter that becomes a load in the operating state of the internal combustion engine with respect to the VVT 50, the current relative rotation angle VT, and the basic control current IBC. That is, by superimposing a dither signal corresponding to changes in various control conditions, it is possible to appropriately eliminate the control rotation angle error when changing the valve timing. As a result, it is possible to control the amount of advance or retard when the valve timing of the VVT 50 corresponding to the change of the control duty ratio is very accurately controlled.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an overall configuration of a valve timing control apparatus for an internal combustion engine according to an example of an embodiment of the present invention.
FIG. 2 is a flowchart showing a processing procedure of an ECU used in the valve timing control device for an internal combustion engine according to an example of the embodiment of the present invention.
FIG. 3 is a map for obtaining the target relative rotation angle in FIG. 2 from the engine speed and the intake air amount.
FIG. 4 is a map for obtaining the basic control current in FIG. 2 from the relative rotation angle deviation.
FIG. 5 is an explanatory diagram showing a dither signal used in the valve timing control apparatus for an internal combustion engine according to an example of the embodiment of the present invention.
FIG. 6 is an explanatory diagram for setting a dither signal used in the valve timing control apparatus for an internal combustion engine according to an example of the embodiment of the present invention according to the current operating state.
FIG. 7 is an explanatory diagram for setting a dither signal used in the valve timing control device for an internal combustion engine according to an example of the embodiment of the present invention in accordance with the current relative rotation angle.
FIG. 8 is an explanatory diagram for setting a dither signal used in the valve timing control apparatus for an internal combustion engine according to an example of the embodiment of the present invention in accordance with the current basic control current.
[Explanation of symbols]
10 Internal combustion engine 11 Crankshaft (drive shaft)
12 Chain 13 Chain sprocket 15 Camshaft (driven shaft)
21 Crank position sensor 22 Cam position sensor 30 ECU (electronic control unit)
40 Spool valve 41 Linear solenoid 50 VVT (Valve timing control mechanism)

Claims (2)

Provided in a driving force transmission system that transmits a driving force from a driving shaft of an internal combustion engine to a driven shaft that opens and closes at least one of an intake valve and an exhaust valve, and either the driving shaft or the driven shaft is in a predetermined angle range. A valve timing control mechanism that is relatively rotatable within
A spool valve for adjusting the hydraulic pressure supplied to the valve timing control mechanism;
Drive shaft rotation angle detection means for detecting the rotation angle of the drive shaft;
Driven shaft rotation angle detecting means for detecting the rotation angle of the driven shaft;
A relative rotation angle that calculates a relative rotation angle that is a phase difference between the rotation angle of the drive shaft detected by the drive shaft rotation angle detection unit and the rotation angle of the driven shaft detected by the driven shaft rotation angle detection unit. Computing means;
Target relative rotation angle calculating means for calculating a target relative rotation angle that is a target phase difference between the rotation angle of the drive shaft and the rotation angle of the driven shaft according to the operating state of the internal combustion engine;
A control rotation angle is calculated according to a deviation between the relative rotation angle calculated by the relative rotation angle calculation means and the target relative rotation angle calculated by the target relative rotation angle calculation means, and a linear solenoid of the spool valve A relative rotation angle control means for controlling the current supplied to the basic control current calculated based on the control rotation angle , and relatively rotating the drive shaft or the driven shaft by the valve timing control mechanism;
A correction rotation angle for giving a minute amplitude fluctuation at a predetermined frequency with respect to the control rotation angle calculated by the relative rotation angle control means is set, and a current supplied to the linear solenoid is set to the basic control current as the predetermined frequency. And a control rotation angle correction means for superimposing and correcting a dither signal corresponding to a correction rotation angle that gives a minute amplitude fluctuation. 2. The internal combustion engine according to claim 1, wherein the magnitude of the amplitude fluctuation at the correction rotation angle is set based on at least one of the operating state of the internal combustion engine, the relative rotation angle, and the control rotation angle. Valve timing control device.

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